You can’t compare albums from different years considering how fast streaming is evolving. Then, a big difference between Ariana and the others you quoted (Bieber, Sheeran, Selena) is that she started after appearance of streaming. The remaining 3 artists have a fanbase used to buy her records, from a generation that did buy records. The huge majority of Ariana’s fans never bought an album in their lifetime. The UK figure is accurate as it is, it has been worked out thanks to weekly ranking inside the streaming chart. In all countries, she always performed insanely better on streams than on sales.

It is obvious and 100% safe and official that DW is nowhere near 1,2m WW – it shipped less than 900k units in 2016 and added only 10% to its shipments in 2017.

Even drake his streams in the UK doesn’t represent +60% of his sales, but to be honest this time i doesn’t have receipts.
I read you use streams to calculate sales (selena) in Asia but isn’t better touring? Also, Ariana is a bigger touring/singles sales/streaming than selena in the UK, Ariana selling only 20k more than her in the UK seems weird.

No way revival sold more than DW in brazil/mexico and almost the same in asia when ariana is by far bigger than her in those markets.
America: 625k
US: 400k
Canada: 50k
Mexico: 85k
Brazil: 50k
Argentina: N/A